1. Field
Embodiments of the present invention generally relate to substrate processing and, more particularly, to methods of processing substrates via physical vapor deposition (PVD).
2. Description of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors and resistors) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. As the dimensions decrease, processing of the integrated chip substrates become increasingly more challenging.
For example, in conventional substrate processing, thin layers of material are applied to the inner surfaces of substrate features prior to filling the feature with conductive material. Ideally, the thin layer would be uniform throughout the feature, with minimal overhang (excessive material on surfaces proximate the opening of the feature), which can reduce the size of the feature opening, or close the opening completely (undesirably leaving an air gap trapped within the feature).
Typical processes commonly used for fabricating integrated circuits having features with a high aspect ratio (e.g., of the height of the feature to the width of the feature) include depositing material in a bottom of the features and re-sputtering the material to facilitate redistribution from the bottom to the sidewalls of the feature. This is done using high energy ions directed toward the substrate. Unfortunately, this method causes damage to the underlying layers and to the substrate itself, particularly at the corners, or bevel, and bottom of the feature. This results in significant line resistance increase and reliability degradation. As the dimensions of the integrated circuit components decrease, the aspect ratio increases, which further increases the above problems.
Therefore, there is a need in the art for improved methods for processing substrates.